A starter for starting an engine of a vehicle is connected to a power supply battery through a starter relay for driving the starter and a starter cutoff relay for preventing the starter from being driven by a circuit failure (for example, refer to JP 2012-202309 A).
A starter control apparatus for controlling a starter described above conventionally performs a failure diagnosis for the starter cutoff relay. That is, when engine starting is requested and a failure diagnosis condition is satisfied, the starter control apparatus supplies the starter relay with a current while rendering the starter cutoff relay to be non-conductive and compares a voltage applied to the starter with a predetermined voltage (0 volt). When the voltage applied to the starter does not exceed the predetermined voltage, the starter control apparatus determines that the starter cutoff relay is normal. When the voltage applied to the starter exceeds the predetermined voltage, the starter control apparatus determines that the starter cutoff relay is abnormal. After the failure diagnosis, the starter control apparatus supplies the starter cutoff relay with a current to start driving the starter while maintaining the current supply to the starter relay.
According to the configuration described above, the timing of starting driving of the starter is delayed by a period of performing the failure diagnosis relative to the timing of generation of the engine starting request. Thus engine starting operation need be improved.